The hybrid of floating stone column by numerical and physical evaluation

Rapid population growth amplifying demand for accommodation and infrastructure has resulted in soft ground being increasingly used in construction. Problems related to soft ground can be remedied by adopting a ground improvement technique. The stone column is one of the most effective and feasible techniques for soft clay soil improvement. Stone columns increase bearing capacity and reduce the settlement of soil. However, soft ground of more than 40 meters depth makes stone column treatment costlier. The design of floating stone columns within soft ground is sometimes needs to adopt. However, this method is not popular compared to the end bearing stone columns due to low mobilised shear resistance and resulted in higher occurrence of punching failure. This research is aimed for addressing the shortcoming floating stone columns with proposing the hybrid dimension floating stone columns. The hybrid stone column size able to increase the mobilised shear resistance, decrease punching failure, and reduce the volume of aggregates. In the present work, finite element analysis was performed using the program PLAXIS 2D. An elastic-perfectly plastic constitutive soil model relation based on the Mohr-Coulomb criterion was utilized to predict the behaviour of soft clay strengthen by stone column. Response Surface Methodology (RSM) was used to optimize the hybrid stone column size with the Design-Expert 6.0.4 software. The laboratory physical model tests were performed based on the sizes of optimum hybrid stone column size proposed by RSM. The results revealed that the optimal parameter of the uniform diameter of 44 mm with a length of 100 mm increases its load bearing capacity of 3260.7 N and the lowest settlement was recorded at a diameter of 24.2 mm with a length of 400 mm to achieve 25.8 mm of settlement. Moreover, the hybrid column size i.e. the first stone column diameter of 43 mm and second diameter of 21.2 mm with the same lengths of 200 mm each diameter able to achieve load-bearing capacity of 3350.9 N and settlement of 24.5 mm. Thus, by comparing with the uniform diameter stone column of 44 mm and length of 400 mm, the hybrid column able to increase the load bearing capacity by 3% and decrease the settlement by 5%. In addition, a good agreement was obtained between the numerical and physical models with variation 25%. In addition, the hybrid stone column size is able to reduce the volume of aggregates up to 40%